1. Field of the Invention
The present invention relates to an absorption chiller, and more particularly to a vapor/liquid separator for use between a generator and a condenser or between an evaporator and an absorber.
2. Description of Related Art
Typical absorption chillers have a working solution from which a refrigerant is cyclically vaporized and reabsorbed to provide a cooling effect. Common solutions consist of water and lithium bromide with water being the refrigerant, or ammonia and water, in which case the ammonia is the refrigerant.
In operation, the solution is heated within a generator to vaporize the refrigerant from the solution. For a solution of lithium bromide and water, the water vaporizes, while the remaining solution becomes more concentrated with lithium bromide. For absorption systems using a solution of ammonia and water, the ammonia is the vaporized component.
After vaporizing the refrigerant in the generator, the remaining liquid concentrated solution returns to an absorber. Meanwhile, the generated refrigerant vapor passes through a vapor/liquid separator before entering a condenser, where the refrigerant vapor condenses.
From the condenser, the refrigerant enters a lower-pressure evaporator. The reduced pressure in the evaporator expands the refrigerant, which lowers the refrigerant""s temperature significantly. Within the evaporator, the refrigerant passes across a heat exchanger to cool what is known as chilled water. The chilled water can then be used as needed, such as to cool rooms or other areas of a building. While in the evaporator, the refrigerant vaporizes as the refrigerant absorbs heat from the relatively warm xe2x80x9cchilled water.xe2x80x9d The refrigerant vapor then passes through another vapor/liquid separator before being drawn into the absorber. Inside the absorber, strong solution returning from the generator reabsorbs the vapor to create a dilute solution. The dilute solution is then pumped back to the generator to perpetuate the solution separation/absorption process.
The effectiveness of the vapor/liquid separators (both, the one between the generator and the condenser and the one between the evaporator and the absorber) can have a significant impact on an absorption chiller""s overall performance. An effective separator should inhibit droplets, entrained by vapor, from being carried over from a vaporizing chamber (e.g., the generator or the evaporator) and into a devaporizing chamber (e.g., the condenser or the absorber). The separator should also inhibit liquid solution from splashing back out of the devaporizing chamber and into the vaporizing chamber.
Ineffective vapor/liquid separation can cause several problems for absorption chillers. For chillers using lithium bromide, for example, concentrated solution splashing back out of the absorber and into the evaporator can cause salt to build up in the evaporator and thus lower the vapor pressure of the refrigerant, resulting in reduced chiller capacity and/or reduced COP (coefficient of performance). Additionally, liquid carryover from the evaporator into the absorber results in lost chiller capacity and/or COP. Liquid carryover from the generator into the condenser eventually results in salt buildup in the evaporator, resulting in lost chiller capacity and/or COP.
Various devices have been developed for separating droplets from a stream of gas or vapor. Examples of such devices are disclosed in U.S. Pat. Nos. 3,490,210; 4,802,901; 5,230,725; 5,269,823; 5,269,009; 5,464,459 and 5,514,193. Although the devices have tortuous flow paths that may be effective as a barrier to droplets, such flow paths may create a significant pressure differential that impedes the flow of vapor. Thus, the devices are not necessarily the most suitable for use in absorption chillers, which can be particularly sensitivity to pressure drops.
With absorption chillers, it is very important to minimize the pressure drop between its generator and condenser and between its evaporator and absorber. A pressure drop across a generator/condenser or an evaporator/absorber separator adversely affects the saturation temperature of the generated refrigerant in both components. A pressure drop across a liquid/vapor separator is detrimental to the performance of the heat exchanger in the absorber and/or generator.
Also, intricate vapor/liquid separators may require equally intricate mounting hardware to hold the separator in place. Such mounting hardware may be costly to build, difficult to install, and/or create an additional obstruction to the flow of vapor. Such hardware inside an absorption chiller is generally inaccessible for repair or replacement, since absorption chillers are usually hermetically sealed. Thus, the mounting hardware is commonly made of relatively expensive stainless steel.
It is an object of the present invention to provide an absorption apparatus with a vapor/liquid separator that includes a series of eliminator blades configured to impede droplets while creating minimal flow resistance to vapor.
Another object of the invention is to provide an eliminator blade that with respect to the direction of vapor flow includes an upwardly inclined upstream leg and a downwardly inclined downstream leg, and further includes a deflection tab that is coplanar with the upstream leg. The tab extends out over the downstream leg to create a concavity that helps prevent liquid from splashing back across the eliminator blade.
Another object of the invention is to optimize the relative size, shape, spacing and orientations of an upstream leg, a downstream leg and a deflection tab of an eliminator blade.
Another object is to provide a single-piece eliminator blade that includes an upstream leg, a downstream leg and a deflection tab.
Yet, another object is to provide an eliminator blade that can be readily manufactured using an inexpensive spot welding process.
A further object is to provide an eliminator blade that is particularly suited for a generator/condenser or an evaporator/absorber of an absorption chiller, wherein liquid may try to splash back in a direction counter to the primary direction of vapor flow.
A still further object is to use a tube support plate of a heat exchanger to support a bank of eliminator blades by having the eliminator blades pass through a series of holes in the plate.
Another object is to ease the installation of a bank of eliminator blades inserted through a series of holes in a tube support plate by providing a slip fit between the blades and the holes.
Another object is to make the eliminator blades of relatively thin stainless steel and to make the tube support plate, which supports the blades, of milder steel that is thicker than the blades. The thinness of the blades provides minimal flow resistance, the stainless steel protects the eliminator blade from corrosion, and the mere thickness of the tube support plate helps the plate tolerate corrosion.
These and other objects of the invention are provided by an absorption apparatus that includes a series of eliminator blades situated between a vaporizing chamber and a devaporizing chamber of an absorption chiller. Each of the blades includes an upstream leg, a downstream leg and a deflection tab. With respect to the direction of vapor flowing from the vaporizing chamber to the devaporizing chamber, the upstream leg is at an upward incline and the downstream leg is at a downward incline. The deflection tab extends out over the downstream leg to create a concavity that helps prevent liquid in the devaporizing chamber from splashing back across the eliminator blade.